Portable locator system and method

ABSTRACT

A tracking and locating system and method which provides for a lightweight and portable tracking locator device. The locating system is easily transferable from one user to another user or from a first object to second object. The locating system also provides power saving and conserving features. The locating system further provides positional information of such locator devices in the form of hypertext markup language pages viewable on the Internet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to locating and tracking system. Moreparticularly, the invention is a tracking and locating system and methodwhich provides for a lightweight and portable tracking locator device,which is easily transferable from one user to another user or from firsta object to a second object, which provides power saving and conservingfeatures associated with the locator device, and which further providespositional information of such locator devices in the form of hypertextmarkup language pages viewable on the Internet.

2. The Prior Art

Wireless devices of all kinds have been in use for pinpointing objects,people and animals on the surface of the earth, under water, or inspace. Some wireless devices also provide navigational information suchas whether or not a moving vessel or vehicle is “on course” to itspredetermined destination. Radio frequency (RF) location and navigationsystems are the oldest, and more recently developed devices function atinfrared (IR) and visible wavelengths. Acoustic location and navigationsystems such as sonar also exist.

Traditional radiolocation is the process of determining the position ofa vehicle, aircraft, or vessel. Radionavigation is the use of radioapparatus, by personnel aboard moving vessels, for the purpose ofplotting and maintaining a course.

The simplest method of radiolocation is known as the “directionalmethod” wherein two or more fixed receiving stations, which areseparated by a fixed distance, receive radio transmission signals from atransmitter that is mounted on a vessel. The vessel location isdetermined from the intersection of great circles drawn outward from thereceiver station points in the appropriate directions.

A second implementation for determining the position of objects involvesradar. The term “radar” is an acronym derived from the words “radiodetection and ranging.” Electromagnetic (EM) waves having certainfrequencies reflect from various objects, particularly if those objectscontain metals or other electrical conductors. Using a transmitter,receiver, and a display at a fixed station, the location of flyingobjects with respect to the fixed location may be determined byascertaining the directions from which radio signal are returned, and bymeasuring the time it takes for an EM pulse to travel from thetransmitter to a target and back. However, such radar systems are notuseful for tracking a ground moving objects, or objects which have poorEM reflective properties. Additionally, radar systems are not normallyuseful for differentiating the identity of objects, particularly whenthere are a plurality of objects.

The most sophisticated radiolocation and radionavigation techniquesemploy the global positioning system (GPS). The GPS is a network ofradiolocation and radionavigation apparatus that operates on a worldwidebasis. The GPS system employs several satellites and allowsdetermination of latitude, longitude, and altitude.

Most recently, vehicle location and navigation systems have been adaptedto track the location of automobiles using the GPS system. Such systemsinclude sensors which are fixed to the automobile and draw power fromeither the car battery or a second large power source. The purpose offixing the automobile tracking sensor to the vehicle is primarily forsecurity reasons. Because one main purpose of the tracking system tolocate the vehicle in cases of theft, it is important that the sensorsystems of the tracking systems be mounted or otherwise fixed to thevehicle, making such sensor systems not easily removed or transportablefrom a first object to a second object. Furthermore, because a largepower source such as a car battery is normally available to suchtracking systems, intelligent power saving or conserving features arenot provided.

Accordingly, there is a need for a tracking and locating system andmethod which provides for a lightweight and portable tracking locatordevice, which is easily transferable from user to user or object toobject, which provides power saving and conserving features associatedwith the locator device, and which further provides positionalinformation of such locator devices in the form of hypertext markuplanguage pages viewable on the Internet. The present invention satisfiesthese needs, as well as others, and generally overcomes the deficienciesfound in the background art.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is a system and method for tracking and locatingone or more objects or persons carrying or otherwise possessing alocator device. The locator device periodically calculates the presentposition of the device from signals received from visible or observableradiolocation transmitters, such as fixed radiolocation towers or globalpositioning system (GPS) satellites. The locator device also maintainsor records its previous locations in order to ascertain the distancetraveled by the locator device. The locator device periodicallycommunicates its positional data to a server computer via a wirelessconnection, which is typically a cellular modem. The rate at which thelocator device periodically transmits its positional data variesaccording to the rate the locator device changes its physical position.If the locator device is relatively stationary, the rate of periodictransmission is reduced to thereby conserve the locator device's powerconsumption. If the locator device is moving rapidly, the rate of periodtransmission is increase to thereby accurately depict the actualposition of the locator device and the person or object in possession ofthe device. The locator device has software running therein forcalculating or otherwise determining the relative movement of thelocator device. The server computer maintains positional data receivedfrom of all the locator devices participating in the system and makessuch positional data available to subscriber users. The system permitssubscriber users to retrieve the positional data of objects or personsthat the subscriber user wishes to track or locate though subscribercomputers. The subscriber computers are linked or otherwise connected tothe server computer using standard networking means, such as an Internetconnection or a dial-up connection. The locator device includes a powersource, such as a battery. Algorithms or routines residing in thelocator device provides power saving features and methods to extend thelife of the power source.

In its most general terms, the system of the invention comprises alocator device having a receiver for receiving signals from visibleradiolocation transmitters, a server computer in wireless communicationwith the locator device, and a subscriber computer operatively coupledfor communication with the server computer. Positional data iscalculated by the locator device from signals received from theradiolocation transmitters. This positional data is communicated fromthe locator device to the server computer, and then communicated fromthe server computer to the subscriber computers via a network or dial-upconnection. The invention provides means for the user of the subscribercomputer to ascertain the location or position of persons or objectspossession the locator device via the subscriber computers. Theinvention may also include power saving or conserving algorithmsassociated with each locator device.

By way of example, and not of limitation, the locator device preferablycomprises a radiolocation receiver operatively coupled to a centralprocessing unit (CPU), and a wireless modem operatively coupled to theCPU. Random access memory (RAM) is coupled to the CPU which executesfunctions and routines associated with the locator device, including,for example, calculating the locator device's position and storing arecord or log of the locator device's past positions and locations.Alternatively, a circuit board having the functions and routinesdescribed herein for carrying out the CPU functions may be provided. Apower source, such as a battery, is provided within the locator device.The radiolocation receiver includes an antenna or radio frequency (RF)transducer which is preferably structured and configured to receiveelectromagnetic frequency waves or signals provided by visible GPSsatellites.

Generally, GPS satellites transmit modulated signal codes containingtiming information which are used by the receiving apparatus to makemeasurements. The receiver examines the RF input stream received intothe antenna and demodulates GPS signals into serial data which iscommunicated to the CPU for further processing. The CPU determines thelocation of the device by measuring the distances to a plurality ofvisible GPS satellites. Normally, the CPU measures distances to four ormore different GPS satellites. The measurement is carried out by timingthe signals traveled between the satellites and the receiver as is knownin the art. Additional correction factors as in known in the art may beused by the CPU to compensate for errors arising from propagation delaysin radio signal travel. From these measurements, the CPU formulates the“positional data” of the device in terms of latitude, longitude, andaltitude.

The wireless modem in the locator device may comprise any wirelesscommunication system such as a cellular modem or personal communicationservices (PCS) system. A cellular modem is preferred because of thepervasiveness of cellular service throughout the world. The CPU carriesout the operation of communicating the positional data of the locatordevice and other information such as its serial number or identificationnumber to a wireless provider, which is preferably a cellular providervia the cellular modem. In response to the received signal from thecellular modem, the cellular provider transfers the received “positionaldata” to a server computer, which is in network communication with thecellular provider.

The server computer stores the positional data of the locator devicesparticipating in the system into its memory. More preferably, thepositional data is stored into a database system residing in the servercomputer as is known in the art. The database includes informationrelated to the locator device such as a serial number or anidentification number, positional data including the most recent dataand historical data, and the date and time when such positional data wasreceived. The database system also includes information related tosubscriber users, such as identity, passwords, and which locator devicesthe subscriber user may track or locate.

The server computer communicates the positional information of thelocator devices to the subscriber users. Preferably, the server computercomprises a World Wide Web (Web) server residing in the server computer.The Web server carries out the operation of publishing hypertext markuplanguage (HTML) pages containing positional data in the form of text andimages. Typically, the server computer will respond to a request from asubscriber computer by executing a query in the database for theinformation requested. The server then merges the positional informationwith a map overlay to produce a convolution image with textualinformation to produce an HTML page, which is then communicated to thesubscriber user for viewing. The HTML page may also include a Java™applet which shows the positional information in a form of an image. TheJava applet may dynamically show the positional movement of the deviceby updating the image of the positional information as the locatordevice changes location. Various other means known in the art may beused to dynamically update the image of the positional informationincluding, for example, a refresh rate which reloads new positional dataimages on the HTML page, or streaming video which depicts the movementof the locator device over a map.

The server computer may employ alternative methods of communicating theposition information of the locator device to the subscriber userincluding proprietary dial-up connection systems such as electronicbulletin board systems (BBS) or AMERICA ONLINE™. Other communicationalternatives include fax, paging, email or phone services providing thesame positional information about the locator device in otherelectronic, paper or voice forms. While the server computer herein isdescribed in terms of a single computer, it is within the scope andspirit of this invention that two or more computers may be utilized tocarry out the operations of the server computer in order to balance thecomputational load among more than one computer.

The subscriber computers include software, which is generally a Webbrowser, for allowing the subscriber user to view the positionalinformation of the locator devices. The subscriber user wishing to trackpersons or objects possessing a locator device will generally access asubscriber computer which is operatively coupled for communication withthe server computer. Normally, subscriber computer is connected to theserver computer through an Internet connection and is equipped with WebBrowser software residing therein. The subscriber user wishing to tracka person or object possessing a locator device will make a request tothe server computer for the location of a particular locator device.Responsive to this request, the server computer will transmit an HTMLpage with the location information to the subscriber user as describedabove. The HTML page is then viewed at the subscriber computer in theform of a graphical user interface (GUI), or alternatively a commandline user interface (CLUI).

According to another aspect of the present invention, the locator deviceincludes power conserving functions, which are generally embodied insoftware running on a processor or other circuitry residing therein forthe optimizing power usage of the locator device. The power conservingfunctions carry out the operation of monitoring the communication linkbetween the locator device and the GPS satellites. When communicationlink between the locator device and two or more GPS satellites isinterrupted, the power conserving functions temporarily interrupttransmission to the server computer, thereby reducing power consumptionwhere the positional data of the locator device is unavailable.Transmission of data to the server computer remains ceased until thecommunication link between the locator device and two or more GPSsatellites is reestablished. Once such a link is reestablished, the datacommunication to the server computer resumes.

The power conserving functions also tracks the distances traveled by theperson or object possessing the locator device by maintaining a historyof data locations formulated by the CPU in memory. This history of datalocations is used for determining the rate of change of positional dataof the person or object in possession of the locator device. Asdescribed earlier, the locator device periodically transmits positionaldata to the server computer at a variable rate dependent upon therelative movement of the locator device. The power conserving functionsincrease the rate of periodic transmission as the relative movement ofthe locator device increase. Conversely, the power conserving functionsdecrease the rate of periodic transmission when the locator deviceremains relatively stationary. This algorithm provides the servercomputer with accurate positional data regardless of the relativemovement of the locator device, and additionally reduces the powerconsumption in the locator device when the device is relativelystationary.

Another aspect of the invention provides that the locator device beeasily transferable from a first user to a second user or from a firstobject to a second object. The locator device is structured andconfigured be compact, lightweight and portable and easily carried withpersons or objects. In an illustrative embodiment, the receiver, theCPU, the memory, and the cellular modem of the locator device aremounted on a circuit board and are housed within a casing unit. Thelocator device includes a clip mounted on the exterior surface of thecasing unit which allows the locator device to be releasably coupled toa user or object. The locator device may thus be attached to and removedfrom a user or object or from the user's clothing such as belts, pants,backpacks or purses.

An object of the invention is to provide a tracking and locating systemwhich overcomes the deficiencies of the prior art.

Another object of the invention is to provide a tracking and locatingsystem and method which provides a lightweight and portable locatordevice which is easily carried with persons or objects.

Another object of the invention is to provide a tracking and locatingsystem and method which provides a portable locator device which iseasily transferable from a first user to a second user or from a firstobject to a second object.

Another object of the invention is to provide a tracking and locatingsystem and method which provides a locator device having powerconserving means for maximizing the life of a power source provided tothe locator device.

Another object of the invention is to provide a tracking and locatingsystem and method which communicates positional data of specific locatordevices to users via a Internet connection and hypertext markup languagepages.

Further objects and advantages of the invention will be brought out inthe following portions of the specification, wherein the detaileddescription is for the purpose of fully disclosing the preferredembodiment of the invention without placing limitations thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood by reference to thefollowing drawings, which are for illustrative purposes only.

FIG. 1 is a block diagram of a locating system in accordance with thepresent invention.

FIG. 2 is a block diagram of an alternative portable locator device.

FIG. 3 is a flowchart showing generally the steps involved in carryingout the power management means of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring more specifically to the drawings, for illustrative purposesthe present invention is embodied in the system shown FIG. 1 throughFIG. 2 and the method outlined in FIG. 3. It will be appreciated thatthe apparatus may vary as to configuration and as to details of theparts, and that the method may vary as to details and the order of thesteps, without departing from the basic concepts as disclosed herein.The invention is disclosed generally in terms of a tracking and locatingsystem and method, although numerous other uses for the invention willsuggest themselves to persons of ordinary skill in the art.

Referring first to FIG. 1, there is shown generally a block diagram of atracking and locating system 10 in accordance with the invention. Thesystem 10 comprises a locator device 12 having means for generatingpositional information of the locator device. The present system isconfigured to locate and track one or more locator devices, eachoperating as locator device 12 as described herein, and each having aunique identifier or serial number associated therewith. The positionalinformation generating means comprises a receiver 14 connected to anantenna 16 and a central processing unit (CPU) 18 connected to memory20. The receiver 14 is operatively coupled for communication with theCPU 18.

A control interface 21 is provided to accept input commands from a userof the locator device 12. The control interface 21 in connected to theCPU 18 for processing of input commands issued at the control interface21 by the user of locator device 12 and to a power source 30 forproviding typical activation means for the locator device 12.

The antenna 16 comprises a standard radio-frequency (RF) transducer asis known in the art for receiving electromagnetic wave signals from aplurality of visible radiolocation transmitters. The term “visible”refers to the ability of the locator device to receive synchronizationsignals and timing signals and other informational data from theradiolocation transmitter. In the preferred embodiment, theradiolocation transmitters comprise global positioning system (GPS)satellites 22 a through 22 n, although land-based radiolocationtransmitters may also be used. The GPS satellites transmit signals inthe UHF part of the radio spectrum, thus the antenna 16 of the preferredembodiment is structured and configured to receive signals in the UHFfrequency range.

The receiver 14 comprises standard circuit stage components or likehardware for detecting and receiving radio frequency signals as in knownin the art and carries out the operation of scanning the input streamreceived by antenna 16 and demodulating GPS signal data into serial datafor use by the CPU 18. In an illustrative embodiment the receiver unit14 is an ASHTECH® G-8 model unit. This serial data produced by thereceiver unit 14 is then communication to the CPU 18 for furtherprocessing as described in more detail below.

GPS satellites 22 a through 22 n transmit signals having special codescontaining information used by various receiving apparatus forcalculating position. The CPU includes program means running thereon fordetermining the location of the locator device 12 as in known in theart. In general, the CPU 18 calculates the distance between the locatordevice 12 and the GPS satellites 22 a through 22 n using the timingsignals provided by the GPS satellites 22 a through 22 n, and carriesout standard radiolocation calculations to formulate “positional data”which is the location of the locator device 12 relative to the positionsof the GPS satellites 22 a through 22 n. The timing signals as well asthe positions of the GPS satellites are communicated to the locatordevice 12 though the code signals transmitted by the GPS satellites 22 athrough 22 n. The positional data formulated by the CPU 18 includeslatitude, longitude, and altitude information about the locator device12. The positional data formulated by the CPU 18 is further maintainedor recorded in a log in the memory 20 for later computation as describedin conjunction with FIG. 3. The CPU 18 also carries out the operationperiodically communicating the computed positional data to a wirelessmodem device for further transmission as described below.

The locator device 12 further comprises a cellular modem 24 operativelycoupled the CPU 18. The cellular modem 24 includes an antenna 26 and maybe any cellular modem or personal communication services (PCS) modem,however a cellular modem is preferred because of the pervasiveness ofcellular service availability. In an illustrative embodiment, thecellular modem 24 comprises a MOTOROLA® 505sd modem. The cellular modem24 carries out the operation of transmitting the positional datareceived from the CPU 18 and communicating such positional data to awireless service provider. Preferably the wireless service provider is acellular service provider 28. The cellular frequency for suchcommunication is typically designated by the cellular provider 28.

The locator device 12 also comprises a power source 30 provided therein.The power source 30 is normally a standard battery. The power source 30provides power to the various elements of the locator device 12including the receiver 14, the CPU 18, the memory 20 and the cellularmodem 24. The CPU 18 communicates with power source 30 via line 32 andincludes program means residing thereon for managing power usage andconsumption of device 12 as described below in conjunction with FIG. 3.

Preferably, the receiver 14, the CPU 18, the memory 20, the cellularmodem 24 are mounted on a circuit board or like hardware device and ishoused within a casing unit (not shown). The power source 30 is alsoprovided within the casing unit. The control interface 21 may beprovided integral with the casing unit or provided on the outer surfaceof the casing unit and preferably includes switches or other similarcontrols (not shown) for accepting external input from a user of thelocator device 12.

The cellular provider 28 is in wireless communication with the locatordevice 12 via radio signals transmitted by the cellular modem 24 for thepurposes of receiving the positional data information transmitted the bylocator device 12. As noted above, in the preferred embodiment, thewireless modem of locator device 12 comprises cellular modem 24, and thewireless service provider is cellular provider 28. Generally, cellularprovider 28 comprises a network of antennas 34 a through 34 n each ofwhich includes means for receiving from and transmitting data to thecellular modem 24 as is generally known in the art. A base device 36 isprovided with the cellular provider 28 and is operatively coupled to thereceiving and transmitting means of the antennas 34 a through 34 n thusforming a “cellular network”. The base device 36 includes means formanaging the communication exchange of the devices participating in thecellular network as in known in the art. The cellular provider 28communicates positional data received from the locator device 12 to aserver computer 38 for further processing.

The server computer 38 comprises a standard computer such as aminicomputer, a microcomputer, a UNIX® machine, mainframe machine,personal computer (PC) such as INTEL®, APPLE®, or SUN® based processingcomputer or close thereof, or other appropriate data processing means.Server computer 38 also includes typical components (not shown), such asa motherboard, central processing unit (CPU), random access memory(RAM), hard disk drive, display adapter, other storage media such asdiskette drive, CD-ROM, flash-ROM, tape drive, PCMCIA cards and/or otherremovable media, a monitor, keyboard, mouse and/or other user interfacemeans, a modem, network interface card (NIC), and/or other conventionalinput/output devices.

The server computer 38 is operatively coupled with the cellular provider28 to receive positional data information, normally through a fast dataconnection means, such as T1, T3, multiple T1, multiple T3, or otherhigh-speed conventional data connection means. Server computer 38 andcellular provider 28 can alternatively connect to each other using astandard Internet connection means, cable means, telephone means,wireless means, or other means for establishing a communication network.Server computer 38 is also operatively coupled to the Internet showngenerally as 41 via a fast connection means, such as T1, T3, multipleT1, multiple T3, or other high-speed conventional data connection means.Alternative methods for connection server computer 38 to the Internet asis known in the art may also be used.

Server computer 38 also has loaded in it RAM a conventional serveroperation system (not shown) such as UNIX, WINDOWS NT, NOVELL, SOLARIS,or other server operating system. Server computer also has loaded in itsRAM web server software 40 and database software 42. The web serversoftware 40 carries out the operation of handing hypertext transferprotocol (HTTP) or Web page request as described further below.

The database software 42 carries out the operation of storing,retrieving, accessing, deleting and updating database information storedin database 44. The database 44 contains information related to eachlocator device 12 of the system 10. Positional data information aboutlocator devices is stored in a tracking table (not shown) within thedatabase 44.

The tracking table includes, for example, a plurality of LID numberscorresponding to each locator device's identifying code or serialnumber, data location information such as latitude, longitude, andaltitude, the date and time when such data location information wasentered, and other pertinent information associated with each LIDnumber. Subscriber data information about subscriber users are stored ina subscriber table (not shown) within the database 44.

The subscriber table includes, for example, a plurality of SID numbercorresponding to each subscriber user, with a username or screen name,e-mail address, password, the LID or locator devices the subscriber maytrack, and other pertinent subscriber user information. The subscribertable is related to the tracking table via the common LID field residingin both tables. Thus positional data information related to a subscribeSID in the subscriber table may be obtained by querying the positionaldata information in the corresponding LID field in the tracking table.

As positional data is received by server computer 38 from the cellularprovider 28, the database software 42 parses the data information intolocator device identity information and positional data information, andstores such information along with the current date and time into thecorresponding fields in the tracking table. Thus the tracking tableconstantly maintains current positional data information of the variouslocator devices participating in the system 10.

A subscriber computer 46 is provided in the system for allowing asubscriber user wishing to track a particular locator device. Subscribercomputer 46, like server computer 38, preferably comprises as standardcomputer such as a minicomputer, a microcomputer, a UNIX® machine,mainframe machine, personal computer (PC) such as INTEL®, APPLE®, orSUN® based processing computer or close thereof, or other appropriatedata processing means.

Server computer 38 also includes typical components (not shown), such asa motherboard, central processing unit (CPU), random access memory(RAM), hard disk drive, display adapter, other storage media such asdiskette drive, CD-ROM, flash-ROM, tape drive, PCMCIA cards and/or otherremovable media, a monitor, keyboard, mouse and/or other user interfacemeans, a modem, and/or other conventional input/output devices.Subscriber computer 46 also loaded in its RAM an operating system (notshown) such as UNIX, WINDOWS 98 or the like.

Subscriber computer 46 further has loaded in ram a Web browser program48 such as NETSCAPE, INTERNET EXPLORER, AOL, or like browsing softwarefor client subscriber computers. Subscriber computer 46 is normallyembodied in conventional desktop or “tower” machine, but canalternatively be embodied in a portable or “laptop” computer, a handheldpersonal digital assistant (PDA), a cellular phone capable of browsingWeb pages, a Internet terminal capable of browsing Web pages such asWEBTV, or other Web browsing devices.

Subscriber computer 46 is operatively coupled for communication with theserver computer 38, typically via the Internet 41 through a phoneconnection using a modem and telephone line (not shown), in a standardfashion. The subscriber user of subscriber computer 46 will typicallydial the user's Internet service provider (ISP) (not shown) through amodem and phone line to establish a connection between the subscribercomputer 46 and the Internet 41. As described above, server computer 38is operatively coupled for communication to the Internet 41. Sincecomputers connected to the Internet 41, are themselves connected to eachother, the Internet 41 establishes a network communication link betweenthe subscriber computer 46 and the server computer 38. Generally,subscriber computer 46 and server computer 38 communicate using theTCP/IP (transfer control protocol/internet protocol). More specifically,the Web browser software 48 residing in the subscriber computer 46communicates with the Web server software 40 residing in the servercomputer 38 via the HTTP protocol. However, other protocols forcommunication may also be utilized, including PPTP, NetBEUI over TCP/IP,and other appropriate network protocols.

The subscriber user of subscriber computer 46 requests positional datainformation by accessing the Web browser software 48 and contacting theWeb server software 40 residing on server computer 38. Normally, asubscriber user will make a request to the server computer 38, which isreceived by Web server software 40. Web server software 40 validates theidentity of subscriber user to ensure that the user requestingpositional data information is the appropriate authorized user. Thisvalidation or authorization is normally carried out though standardchallenge/response security authentication involving a user name and apassword.

Once the subscriber user is validated, the Web server software 40 issuesa query to the database software 42 for positional data of locatordevices which the subscriber user is authorized to track or locate.Response to this query request, the database software 42 formulates aquery to extract positional data from the tracking table in the database44 and returns the query result to the Web server 40. After receivingthe positional data from the database software 42, the Web server 40merges the positional data with textual information and convolves thepositional data with a map overlay to produce a image having thepositional data superimposed on a map image. Various mapping softwareprograms available in the art may be used for convolving the positionaldata information. The Web server 40 then transmits the textual and imagepositional data information in the form of hypertext markup language(HTML) to the subscriber user accessing the subscriber computer 46 forviewing thereon using the Web browsing software 48.

The HTML page presented to the subscriber may also include a Java™applet which shows the positional information in a form of an image. TheJava applet may dynamically depict the positional movement of the deviceby updating or refreshing the image of the positional information as thelocator device 12 changes location. Various other means known in the artmay be used to dynamically update the image of the positionalinformation including, for example, a refresh rate which reloads newpositional data images on the HTML page, or streaming video such asRealVideo™, Quicktime™, VDO™, MPEG or other like streaming videotechnologies. Such steaming videos depict the movement of the locatordevice over a map background.

Referring now to FIG. 2, a block diagram of an alternative locatordevice is shown and designation as 50. Locator device 50 carries outsubstantially the same functions as described above for locator device12. To this end, the locator device 50 includes means for generating itspositional data information connected to memory 52, a cellular modem 54connected to the positional information generating means, a power supply56, a control interface 58 connected to the positional informationgenerating means, and power management module 59.

The means for generating positional data information comprises a GPSreceiver 60 connected to an antenna 62, and a radio detection finding(RDF) unit 64 connected to the GPS receiver 60. The GPS receiving 60,like receiver 14, comprises standard circuit stage component fordetecting and receiving radio frequency signal as in known in the artand carries other operation of scanning the input stream received byantenna 62. The receiver 60 demodulates GPS signals from the inputstream into serial data for use by the RDF unit 64 to ascertain thepositional data of locator unit 50 as described further below. Theantenna 62, like antenna 16, comprises a RF transducer as in known inthe art and is structured and configured to receive GPS signals producedby satellites 22 a through 22 n.

The RDF unit 64 comprises circuitry or like hardware having means forcalculating its distance from visible GPS satellites 22 a through 22 nusing the timing signals provided by the GPS satellites 22 a through 22n. The calculating means of the RDF unit 64 comprises standardradiolocation calculation methods as is known in the art. Thecalculation means of the RDF unit 64 further formulates its positionaldata in the form of latitude, longitude, and altitude, from the abovementioned calculation methods. This positional data is maintained orrecorded in a log in the memory 52 for later computation, and iscommunicated to the cellular modem 54 for further transmission asdescribed below.

The power supply 56 is normally a battery supply and provides power tothe various elements of the locator device 50, including the GPSreceiver 60, the RDF unit 64, the power management module 59, the memory52, and the cellular modem 54.

The controller interface 58, like control interface 21, carries out theoperation of interpreting external commands issued by the user oflocator device 50 and communicating such commands to the RDF unit 64 andthe power management module 59. For example, when the user of locatordevice 50 activates the unit by pressing an activation switch (notshown) on the control interface, a signal is communicated to the powermanagement module 59 to activate the power supply 58 which providespower to the corresponding elements of the device 50. Alternatively, asimple switch (not shown) connected to the power supply 56 could beprovided at the control interface 58, to provide similar activationmeans.

The cellular modem 54, like cellular modem 24, comprises standardcircuitry for cellular communication and modulation and includes anantenna 66 connected thereto. In an illustrative embodiment, thecellular modem 54 comprises a MOTOROLA® 505sd modem. The cellular modem54 carries out the operation of transmitting the positional datareceived from the RDF unit 64 and communicating such positional data tothe cellular provider 28.

The method and operation of the invention will be more fully understoodby reference to the flow chart of FIG. 3. FIG. 3 illustrates generallythe steps associated with the power management means of the invention.The order of steps as shown in FIG. 3 are only exemplary, and should notbe considered limiting.

Referring now to FIG. 3, as well as FIG. 1, the method of managing orconserving power provided to the locator device 12 is shown.

At step 100, a user of the locator device 12 accessing the controlinterface 21 to signal an activation or “power on” signal. Thisactivation signal is communicated from the control interface 21 to thepower source 30. As described above, switches or other controls may beprovided at the control interface 21 to allow the user to communicatecontrol signals, such as “power on” to the locator device 12.

At step 110, responsive to this activation signal from the controlinterface 21, the power source 30 provides power to, inter alia, thewireless receiver 14, the CPU 18, the memory 20, and the cellular modem24. The locator device is capable at running at a plurality of powerlevels including at least a “normal” level and a “low” level. At the“normal” level, the CPU 18 is running at its highest clock speed andpower is provided at the highest level to all the elements of thelocator device 12, including the wireless receiver 14, the CPU 18, thememory 18, and the cellular modem 24 among others. At the “low” level”,the CPU 18 is running at a reduced clock speed which is normally halfthe speed of the highest clock speed, and one or more of the otherelements are disabled, shutdown or otherwise provided less power by thepower supply. More particularly, communication to the cellular provider28 via the cellular modem 24 is temporarily interrupted. Normally thepower delivered to the cellular modem 24 is interrupted.

Various other intermediary levels may be arranged to provide variouspower level consumption of the power source 30. The CPU 18 carries outthe operation of the managing the power level in which the locatordevice 12 operates by communicating power level signals to the variouselements of the locator device 12, including the power source 30, thewireless receiver 14, and the cellular modem. Initially, during thepower on stage of step 110, the CPU 18 sets the locator device tooperate at the “normal” level.

At step 120, the CPU 18 carries out an internal check of the locatordevice 12. The internal check comprises steps of checking thefunctionality of the wireless receiver 14, the memory 20, the CPU 18,the cellular modem 24, the power source 30, and the control interface21, among other elements. The CPU 18 also ascertains its serial numberor identification number, which may be preprogrammed into a circuit orlike hardware device (not shown) such as a ROM chip, which connected tothe CPU 18 and provided in the locator device 12. The CPU 18 also loadsinto memory 20 software or program means for computing positional data.The software may be provided internally in a circuit or like hardware(not shown) connected to the CPU 18 and provided in the locator device12, or may alternatively be downloaded during this step from thecellular provider 28 via the cellular modem 24.

At step 130, the wireless receiver 14 attempts to synchronize with thevisible GPS satellites 22 a through 22 n. The wireless receiver 14examines the input stream received into the antenna 16 to ascertainsynchronization signals or codes which are transmitted by the GPSsatellites 22 a through 22 n. These synchronization codes are used bythe receiver 14 to ascertain, among other things, the timing signalsnecessary to calculate positional data of the locator device 12.Normally, the locator device requires the timing signals from at leasttwo (2) visible GPS satellites in order to calculate its positionaldata. As noted above, the term “visible” refers to the ability of thelocator device 12 to receive synchronization signals, timing signals andother informational data from the GPS satellites 22 a through 22 n. Theaccuracy of the calculation of the positional data is proportional tothe number of GPS satellites “visible” to the wireless receiver 14.

At step 140, the CPU 18 make a determination whether the wirelessreceiver 14 has synchronized with at least two visible GPS satellites ascarried out during the synchronization step of 130. If the CPU 18determines that the wireless receiver 14 has synchronized with at leasttwo visible GPS satellites, steps 140 through 170 are carried out,otherwise steps 180 through 210 are carried out.

At step 150, the wireless receiver 14 carries out the steps of receivinginput stream data from the antenna 16 and demodulating GPS signals intoserial data as described above. This serial data is then communicated tothe CPU 18 for further processing in step 160.

At step 160, the CPU 18 carries out the steps of receiving the serialdata from wireless receiver 14 and computing positional data of thelocator device 12, as described above. In general the software runningon CPU 18 and in memory 20 calculates the distance between the locatordevice 12 and the GPS satellites synchronized with in step 130 or step190 using the timing signals provided by the GPS satellites, and carriesout standard radiolocation calculations to formulate the positional datawhich is the location of the locator device 12 relative to the positionsof the GPS satellites 22 a through 22 n. The calculated positional datais internally stored in a log or record in the memory 20 for futurecomparison. Also at step 160, the CPU 18 compares the currentlycalculated positional data with the previously calculated positionaldata if any to ascertain the velocity or the relative “positionalchange” of locator device 12.

At step 170, the CPU 18 makes a determination of whether the relative“positional change” calculated in state 160 has increased. As notedabove, the locator device 12 periodically communicates positional datato the cellular provider 28. In order to conserve the power source 30,the locator device 12 will decrease the rate of periodic transmission tocellular provider 28 when the locator device 12 is relativelystationary. Conversely, in order to provide accurate positional data tothe server computer 38 via cellular provider 28, the rate of periodictransmission from locator device 12 to cellular provider 28 is increasedwhen the relative “positional change” determined to have increased. Ifthe locator device 12 remains at a relatively contact rate of velocity,then the rate of transmission remains relatively constant as well. Ifthe “positional change” has increased, step 220 is carried out,otherwise, steps 230 is carried out.

At step 220, the periodic rate at which the cellular modem 24 transmitspositional data to the cellular provider 28 is increased. This stepprovides the server computer 38 with an increased rate of positionaldata where the locator device is found to be moving rapidly. Steps 130and 140 are carried out again.

At step 230, the CPU 18 makes a determination of whether the relative“positional change” calculated in step 160 has decreased. If the“positional change” has decreased, step 240 is carried out, otherwise,steps 130 and 140 are carried out again.

At step 240, the periodic rate at which the cellular modem 24 transmitspositional data to the cellular provider 28 is decreased. This stepsconserves power consumption in the locator device 12 when the device 12is relatively stationary. Steps 130 and 140 and then repeated.

Steps 180 through 210 are carried out when the CPU 18 determines thatthe wireless receiver 14 has not synchronized with at least two visibleGPS satellites in step 140.

At step 180, the locator device 12 is set to the “low” level ofoperation described above in order to conserve the power usage drawnfrom the power source 30. At this level the CPU 18 runs at a reducedclock speed which is normally half of the highest clock speed. The powerto the cellular modem is also terminated or otherwise reduced.Additionally, cellular communication between cellular modem 24 and thecellular provider 28 is temporarily interrupted.

At step 190, the locator device 12 attempt to synchronize with visibleGPS satellites using the same steps as carried out in step 130.

At step 200, the CPU 18 makes a determination whether the wirelessreceiver 14 has synchronized with at least two visible GPS satellitesduring the synchronization step of 190. If the CPU 18 determines thatthe wireless receiver 14 has synchronized with at least two visible GPSsatellites, step 210 is carried out, otherwise steps 190 and 200 arecarried out again.

At step 210, the locator device 12 is restored to the “normal” level ofoperation described above. At this level, the CPU 18 operates at itsfastest clock speed, and power is delivered at the “normal” to theelements of locator device 12 as described earlier in the power on step110. Cellular communication between cellular modem 24 and cellularprovider is also resumed. Steps 150 through 170 are then carried out.

Accordingly, it will be seen that this invention provides a tracking andlocating system and method which provides for a lightweight and portabletracking locator device, which is easily transferable from user to useror object to object, which provides power saving and conserving featuresassociated with the locator device, and which further providespositional information of such locator devices in the form of hypertextmarkup language pages viewable on the Internet. Although the descriptionabove contains many specificities, these should not be construed aslimiting the scope of the invention but as merely providing anillustration of the presently preferred embodiment of the invention.Thus the scope of this invention should be determined by the appendedclaims and their legal equivalents.

What is claimed is:
 1. A locator system comprising: at least one locatordevice having a receiver structured and configured to receiveelectromagnetic frequency signals from a plurality of visibleradiolocation transmitters and generate positional data of said locatordevice from said electromagnetic frequency signals; a cellular modemoperatively coupled to said locator device to transmit said positionaldata; a telecommunication provider in wireless communication with saidcellular modem to receive said positional data from said cellular modem;a server computer in network communication with said telecommunicationprovider to receive said positional data from said telecommunicationprovider, said server computer having software residing therein topublish said positional data; a subscriber computer in networkcommunication with said server computer to receive and display saidpositional data; and a power source coupled to said locator device andto said cellular modem, said locator device including power conservingsoftware residing therein, said power conserving software carrying outthe operation of monitoring synchronization of said receiver with saidradiolocation transmitters, reducing power to said cellular modem whensaid synchronization is lost, and restoring power to said cellular modemwhen said synchronization is reestablished.
 2. The locator system asrecited in claim 1, wherein said software residing in said servercomputer comprises web server software, said subscriber computer furthercomprising web browser software residing therein, said web serversoftware providing said positional data of said locator device to saidweb browser software, said positional data provided to said web browsersoftware structured and configured as hypertext markup language pages.3. The locator system as recited in claim 2, wherein said hypertextmarkup language pages further include Java applets, said Java appletsproviding dynamic images of said positional data.
 4. The locator systemas recited in claim 1, wherein said locator device is releasably coupledto a user.
 5. The locator system as recited in claim 1, wherein saidlocator device is releasably coupled to an object.
 6. The locator systemas recited in claim 1, wherein said cellular modem has a rate oftransmission with said telecommunications provider, said powerconserving software carrying out the operation of calculating the rateof change of position of said locator device, reducing said rate oftransmission to said telecommunication provider when said rate of changeof position decreases, and increasing said rate of transmission to saidtelecommunication provider when said rate of change of positionincreases.
 7. The locator system as recited in claim 1, wherein saidradiolocation transmitters comprise global positioning systemsatellites.
 8. A locator system comprising: at least one locator device,having a receiver and a CPU coupled to said receiver, said receiverstructured and configured to receive electromagnetic frequency signalsfrom a plurality of visible global positioning satellite transmitters,said receiver further structured and configured to convert saidelectromagnetic frequency signals into serial data, said receiverfurther structured and configured to communicate said serial data tosaid CPU, said CPU having software residing therein which generatespositional data of said locator device from said serial data; a cellularmodem coupled to said locator device, said CPU further having softwareresiding therein which communicates said positional data to saidcellular modem; a telecommunication provider in wireless communicationwith said cellular modem to receive said positional data of said locatordevice from said cellular modem; a server computer in networkcommunication with said telecommunication provider to receive saidpositional data of said locator device from said telecommunicationprovider, said server computer having software residing therein topublish said positional data; a subscriber computer in networkcommunication with said server computer to receive said positional data,said positional data viewable on said subscriber computer; and a powersource coupled to said locator device and to said cellular modem, saidlocator device including a power conserving software, said powerconserving software carrying out the operation of monitoringsynchronization of said receiver with said plurality of visible globalpositioning satellite transmitters, reducing power to said cellularmodem when said synchronization is lost, and restoring power to saidcellular modem when said synchronization is reestablished.
 9. A methodfor locating a locator device comprising: receiving electromagneticfrequency signals from a plurality of visible radiolocationtransmitters; generating positional data of said locator device fromsaid electromagnetic frequency signals; transmitting said positionaldata from a cellular modem; receiving said positional data transmittedfrom said cellular modem by a telecommunication provider in wirelesscommunication with said cellular modem; providing said positional datato a server computer networked with said telecommunication provider;publishing said positional data in said server computer; linking asubscriber computer in network communication with said server computerto receive and display said positional data; providing power to saidcellular modem; monitoring synchronization of said locator device withsaid radiolocation transmitters; reducing power to said cellular modemwhen said monitoring synchronization determines synchronization is lost;and restoring power to said cellular modem when said monitoringsynchronization determines synchronization is reestablished.
 10. Themethod as recited in claim 9, wherein said publishing said positionaldata is carried out by a web server software loaded in said servercomputer.
 11. The method as recited in claim 9, further comprising:calculating rate of change of position of said locator device from saidpositional information; reducing rate of transmission by said cellularmodem when said calculating rate of change of position determines rateof change of position has decreased; and increasing rate of transmissionby said cellular modem when said calculating rate of change of positiondetermines rate of change of position has increased.